JPH05164496A - Fin tube for open rack type carburetor - Google Patents

Abstract

PURPOSE:To obtain a fin tube for an open rack type carburetor in which a surface of the fin tube can be protected for a long period even in an environment in which icing and deicing of sea water are repeated. CONSTITUTION:A fin tube of a predetermined shape is molded by an extrusion molding method by using a clad material externally engaged with an Al-Zn alloy tube 11 to be cladded on an outer periphery of a rodlike base ingot 10, and a star-shaped fin tube 14 in which a sacrificial anode film 12 having a predetermined thickness is cladded on its surface is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a fin tube such as a star fin used in an open rack type vaporizer. The fin tube surface is clad with a sacrificial anodic coating of Al--Zn alloy to remarkably improve corrosion resistance. Open rack type carburetor fin tube.

[0002]

2. Description of the Related Art As a vaporizer for vaporizing a liquefied natural gas (hereinafter referred to as LNG) using a heat medium such as seawater, an open rack type vaporizer has hitherto been the mainstream.

As shown in FIG. 2, the open rack type carburetor has, for example, a fin tube 1 having a pair of large fins protruding in the diametrical direction arranged in the fin direction to form a single panel, and its upper and lower ends. The header tanks 3 and 4 are provided in the section to form a heat exchange panel 2, a plurality of panels 2 are arranged in parallel, and heat exchange of seawater as a heat medium is performed from a sprinkler 5 arranged above each heat exchange panel 2. It has a structure that allows it to flow down to the panel 2 surface.

The carburetor having the above structure supplies LNG from the lower header tank 4 provided at the lower end of the heat exchange panel 2, and the LNG flows through the fin tube 1 by the seawater sprinkled from the upper portion of the heat exchange panel 2. As it rises, it is heated and vaporized by seawater that is a heat medium outside the pipe, and is supplied to the outside as natural gas from an upper header tank 3 provided at the upper end of the heat exchange panel 2.

The fin tube 1 forming the heat exchange panel 2 has a structure in which a pair of large fins are projected as shown in FIG. 2, or a so-called star fin tube in which a large number of radial fins are provided to expand the heat receiving area. There is. Further, since the heat exchange panel has a large size of about 4 to 6 m, the fin tube is manufactured by extruding an aluminum ingot into a desired shape.

As described above, since seawater is used as the heat medium in the open rack type vaporizer, A3203, A505
Corrosion-resistant aluminum such as 2 materials is used, but some kind of anticorrosion means is indispensable for protecting the surface of the fin tube because it is constantly exposed to seawater, and since the fins are projecting, thermal spraying is easy for film formation. The formation of sacrificial anodic coatings by the method is common.

More specifically, first, a required surface roughness, that is, a required uneven surface is formed on the fin tube surface by blasting with alumina having a required particle size, and then the Al--Zn alloy is heated and melted to form a jet. The surface of the fin tube was blown with gas to form an Al-Zn alloy coating film.

[0008]

However, the sacrificial anode coating by the thermal spraying method has a relatively short life and is easily peeled off in the application of the open rack type vaporizer, and the thermal spraying film is again provided, but the film thickness is also uneven. Therefore, there was a problem that it was easily peeled off.

When the peeling of the sprayed film was investigated,
The sprayed film is a stack of fine alloy particles, not a metallic structure,
It was also found that the tube base material was adhered only by the anchor effect due to the uneven surface formed by blasting, and when the film thickness was increased to a certain extent or more, it was easily peeled off.
Furthermore, since the fin tube forming the heat exchange panel repeats ice accretion and deicing, it acts mechanically to peel off the sprayed film, resulting in severe wear of the film compared to general use of the sprayed film, It turns out that it will come off in a short period of time.

In view of the present state of the fin tube anticorrosion means, the present invention is for an open rack type vaporizer having a structure capable of protecting the surface of the fin tube for a long period of time even in an environment where seawater is repeatedly frozen and thawed. The purpose is to provide fin tubes.

[0011]

According to the present invention, in a fin tube made of aluminum constituting a heat exchange panel of an open rack type vaporizer, a sacrificial anode coating is clad on the surface of an aluminum base material forming the fin tube. It is a fin tube for an open rack type carburetor characterized by the above.

[0012]

According to the present invention, Al-Zn is formed on the fin tube surface.
The alloy sacrificial anode coating is characterized by being significantly improved in corrosion resistance, but the sacrificial anode coating clad on the base material has a very high bonding force with the base material and there is no risk of peeling, as described later. Also, since it is possible to form a thick film of 1 mm or more, it is possible to protect the base material for a long period of time even in an environment where seawater is repeatedly frozen and thawed. In addition, the sacrificial anode coating to be clad has a self-potential that becomes base in seawater with respect to the corrosion-resistant aluminum material used for the fin tube base material, for example, Al-containing 1-2% Zn.
Zn alloy is most suitable for the anticorrosion effect.

In the present invention, the clad method is, for example, as shown in FIG. 1, an Al-Zn alloy tube 11 for cladding on the outer peripheral surface of a tubular or rod-shaped base material ingot 10.
By preparing a clad material that is fitted to the outside of the clad material and molding the clad material into a fin tube having a required shape by a conventionally known extrusion molding method, a star fin tube 14 having a sacrificial anode coating 12 having a required thickness clad on its surface is obtained. be able to.

The sacrificial anode coating 12 clad to the base material 13 by the extrusion molding method does not peel off because the bonding force with the base material is uniform and it adheres to the base material with extremely high strength. By appropriately selecting the thickness of the Al-Zn alloy tube 11 and the rolling rate at the time of extrusion molding, the thickness can be freely set, and for example, a thick film of 1 mm or more can be formed.

[0015]

Example A70 at the time of extrusion molding shown in FIG.
A 72-fin star fin tube according to the present invention was manufactured by clad 72 materials with an average thickness of 300 μm on the surface of the A3203 base material.

For comparison, the same shape of A3203 material,
After molding an 8-fin type star fin tube of a size, a conventional fin tube was manufactured by forming an Al-Zn alloy sprayed film to an average thickness of 150 μm.

Two kinds of star fin tubes were subjected to a wet and dry alternate immersion test. After the above test, the surface properties of the two types of star fin tubes were examined. As a result, the conventional sprayed coating was heavily worn, the film thickness was significantly reduced, and about 5% of the surface was peeled off. On the other hand, in the star fin tube of the present invention having the clad coating, some pitting was observed, but there were no places where the surface of the base material was consumed.

[0018]

The fin tube for an open rack type carburetor according to the present invention has Al-Zn on the surface of the fin tube.
By forming a thick sacrificial anodic coating by clad alloy material, the corrosion resistance can be significantly improved compared to the conventional sprayed alloy coating.For example, it can be easily clad during extrusion molding, which facilitates manufacturing. In addition, since it is possible to eliminate the need for the labor-intensive spraying film forming work and the regular re-film forming work as in the past, the manufacturability is excellent,
There is an advantage that maintenance is extremely easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a material showing a manufacturing process of a star fin tube according to the present invention.

FIG. 2 is a perspective explanatory view showing an open rack type vaporizer.

[Explanation of symbols]

 1 Fin Tube 2 Heat Exchange Panel 3 Upper Header Tank 4 Lower Header Tank 5 Sprinkler 10 Base Material Ingot 11 Al-Zn Alloy Tube 12 Sacrificial Anode Coating 13 Base Material 14 Star Fin Tube

Front page continuation (72) Inventor Yu Akiyama 1-10 Fuso-cho, Amagasaki-shi, Hyogo Sumitomo Precision Industries Co., Ltd. (72) Yoshitoshi Nakamura 1-10 Fuso-cho, Amagasaki-shi, Hyogo Sumitomo Precision Industries Within the corporation

Claims (1)

[Claims] 1. A fin tube made of aluminum, which constitutes a heat exchange panel of an open rack type vaporizer,
A fin tube for an open rack type vaporizer, wherein a sacrificial anode coating is clad on the surface of an aluminum base material forming the fin tube.